ved that my memory is faulty --- by checking the v7 manuals
I see that the \{ \} notation does not date back that far. But even
given that experience, I still stick to my memory's claim that \{ \}
is older and more widespread than \| and \?; at any rate, POSIX.2
mandates \{ \} for BREs, but only implicitly allows \? and \|.
--Ken Pizzini
All descendents of Bell Lab's v7 sed (at
least; I don't have first hand experience with older seds) have
supported it, and it would be a major incompatability for any other
sed to have failed to support it.
--Ken Pizzini
